How do I tell if my mash and sparge went well.

phuff7129 · 02-07-2012, 05:55 PM

I just got done mashing and sparging my grains for a partial mash. Everything seemed to go well but how do I know if maybe my gravity might be a little low or a little high maybe I wont add as much dme or maybe add more dme. My preboil gravity on 3.5 gallons preboil volume was 1.058 adjusted for temp. My recipe says to add 5lbs of dme at 15 minutes and I am shooting for a 1.072 to 1.076. is there anyway to know before i finish the boil and top up?

**mikeysab** · 02-07-2012, 06:00 PM

Cool down enough wort to take a hydro reading and check. If you have a refractometer, even better. How much grain did you mash? Most of your gravity should come from extract, so I'd say its pretty hard to miss by a whole lot.

TyTanium · 02-07-2012, 06:06 PM

Target: 5.5 gallons x 72 OG = 396 gravity points

Right now you have 3.5 gallons x 58 SG = 203 gravity points,
So you need 396 - 203 = 193 more to get to your target.

Each pound of DME adds 45 points, so 193 / 45 = 4.29#

If you added the full 5 pounds, you'd be at 1.078
=203 mash + 225 (=5x25) DME = 428 / 5.5gal = 78

phuff7129 · 02-07-2012, 06:07 PM

i just measured my pre boil gravity adjusted for temperature is reading 1.064. I mashed 8.25 pounds of grain.

phuff7129 · 02-07-2012, 06:08 PM

Thank you. I just have to learn the math. Now does gravity go up or down when you boil or does it stay the same?

TyTanium · 02-07-2012, 06:11 PM

Still 3.5 gallons? Measuring volume correctly is just as important as gravity readings for efficiency / pre-fermenter readings.

TyTanium · 02-07-2012, 06:12 PM

Gravity increases.

It's simply a ratio of dissolved sugars to volume. As you boil, you lose volume, so your concentration of sugar goes up, and your gravity goes up.

phuff7129 · 02-07-2012, 06:14 PM

I am sure I am going to boil off close to a gallon over 90 minutes but I am going to add the dme but I would think my post boil volume will be less than 3.5 gallons.

phuff7129 · 02-07-2012, 06:22 PM

Thank you very much for your help. It was very informative. I know its hard to know for sure but does it sound like I had a pretty efficient mash?

TyTanium · 02-07-2012, 06:26 PM

Good news is that your boiloff rate doesn't matter since you can just add it back with your top-off water.

What I meant by volume being important is when you take pre-boil gravity readings.
5 gallons at 1.050 is obviously very different than 3.5 gallons at 1.050...same gravity, but there's obviously lots more sugars in the 5 gallons.
5g x 50 = 250 gravity points vs 3.5 x 50 = 175 gravity points. When you boil, your concentration changes, but your total gravity points remain the same. Does that make sense? I find it easier to think in terms of total gravity points instead of specific gravity.
Gravity points only change when I add/remove sugars. Specific gravity changes both with changes in sugars, and changes in water volume.